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Confirmation of co-denitrification in grazed grassland.

Selbie DR, Lanigan GJ, Laughlin RJ, Di HJ, Moir JL, Cameron KC, Clough TJ, Watson CJ, Grant J, Somers C, Richards KG - Sci Rep (2015)

Bottom Line: Pasture-based livestock systems are often associated with losses of reactive forms of nitrogen (N) to the environment.We report that 55.8 g N m(-2) (95%, CI 38 to 77 g m(-2)) was emitted as N2 by the process of co-denitrification in pastoral soils over 123 days following urine deposition (100 g N m(-2)), compared to only 1.1 g N m(-2) (0.4 to 2.8 g m(-2)) from denitrification.This study provides strong evidence for co-denitrification as a major N2 production pathway, which has significant implications for understanding the N budgets of pastoral ecosystems.

View Article: PubMed Central - PubMed

Affiliation: Teagasc, Johnstown Castle, Environmental Research Centre, County Wexford, Ireland.

ABSTRACT
Pasture-based livestock systems are often associated with losses of reactive forms of nitrogen (N) to the environment. Research has focused on losses to air and water due to the health, economic and environmental impacts of reactive N. Di-nitrogen (N2) emissions are still poorly characterized, both in terms of the processes involved and their magnitude, due to financial and methodological constraints. Relatively few studies have focused on quantifying N2 losses in vivo and fewer still have examined the relative contribution of the different N2 emission processes, particularly in grazed pastures. We used a combination of a high (15)N isotopic enrichment of applied N with a high precision of determination of (15)N isotopic enrichment by isotope-ratio mass spectrometry to measure N2 emissions in the field. We report that 55.8 g N m(-2) (95%, CI 38 to 77 g m(-2)) was emitted as N2 by the process of co-denitrification in pastoral soils over 123 days following urine deposition (100 g N m(-2)), compared to only 1.1 g N m(-2) (0.4 to 2.8 g m(-2)) from denitrification. This study provides strong evidence for co-denitrification as a major N2 production pathway, which has significant implications for understanding the N budgets of pastoral ecosystems.

No MeSH data available.


Related in: MedlinePlus

The effect of the nitrification inhibitor DCD on soil ammonium and nitrate concentrations in urine-affected soil, measured from aligned small plots receiving the same treatments as lysimeters in the main study.Error bar is the standard error of the mean (n = 4).
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f4: The effect of the nitrification inhibitor DCD on soil ammonium and nitrate concentrations in urine-affected soil, measured from aligned small plots receiving the same treatments as lysimeters in the main study.Error bar is the standard error of the mean (n = 4).

Mentions: In order to investigate the underlying drivers of the N2 emissions, we assessed the effect of nitrification on both N2TRUE and N2CO, using the nitrification inhibitor dicyandiamide (DCD) which was applied within a subset of 15N-labelled urine treatments. Incorporating DCD with the urine inhibited the first stage of nitrification, the oxidation of NH4+ to NO2− (Fig. 4). Over the first 30 days of the experiment, when the nitrification inhibition was effective, cumulative N2 emissions were significantly (P < 0.05) reduced by 55% for N2CO and no significant changes were found for N2TRUE (Fig. 5). This indicates that reduced NO2− formation, resulting from nitrification inhibition, affected N2CO. This finding, combined with the significantly higher N2CO contribution to the N2 flux than from N2TRUE (Fig. 3), indicates that different N pools supplied each process. The reduced nitrification activity in the presence of DCD and associated reduction in N2CO flux demonstrates that one source pool for co-denitrification (the applied N contribution) was the NO2− produced during nitrification (oxidation of NH4+ to NO2−), rather than true denitrification (reduction of NO3− to NO2−)37.


Confirmation of co-denitrification in grazed grassland.

Selbie DR, Lanigan GJ, Laughlin RJ, Di HJ, Moir JL, Cameron KC, Clough TJ, Watson CJ, Grant J, Somers C, Richards KG - Sci Rep (2015)

The effect of the nitrification inhibitor DCD on soil ammonium and nitrate concentrations in urine-affected soil, measured from aligned small plots receiving the same treatments as lysimeters in the main study.Error bar is the standard error of the mean (n = 4).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663629&req=5

f4: The effect of the nitrification inhibitor DCD on soil ammonium and nitrate concentrations in urine-affected soil, measured from aligned small plots receiving the same treatments as lysimeters in the main study.Error bar is the standard error of the mean (n = 4).
Mentions: In order to investigate the underlying drivers of the N2 emissions, we assessed the effect of nitrification on both N2TRUE and N2CO, using the nitrification inhibitor dicyandiamide (DCD) which was applied within a subset of 15N-labelled urine treatments. Incorporating DCD with the urine inhibited the first stage of nitrification, the oxidation of NH4+ to NO2− (Fig. 4). Over the first 30 days of the experiment, when the nitrification inhibition was effective, cumulative N2 emissions were significantly (P < 0.05) reduced by 55% for N2CO and no significant changes were found for N2TRUE (Fig. 5). This indicates that reduced NO2− formation, resulting from nitrification inhibition, affected N2CO. This finding, combined with the significantly higher N2CO contribution to the N2 flux than from N2TRUE (Fig. 3), indicates that different N pools supplied each process. The reduced nitrification activity in the presence of DCD and associated reduction in N2CO flux demonstrates that one source pool for co-denitrification (the applied N contribution) was the NO2− produced during nitrification (oxidation of NH4+ to NO2−), rather than true denitrification (reduction of NO3− to NO2−)37.

Bottom Line: Pasture-based livestock systems are often associated with losses of reactive forms of nitrogen (N) to the environment.We report that 55.8 g N m(-2) (95%, CI 38 to 77 g m(-2)) was emitted as N2 by the process of co-denitrification in pastoral soils over 123 days following urine deposition (100 g N m(-2)), compared to only 1.1 g N m(-2) (0.4 to 2.8 g m(-2)) from denitrification.This study provides strong evidence for co-denitrification as a major N2 production pathway, which has significant implications for understanding the N budgets of pastoral ecosystems.

View Article: PubMed Central - PubMed

Affiliation: Teagasc, Johnstown Castle, Environmental Research Centre, County Wexford, Ireland.

ABSTRACT
Pasture-based livestock systems are often associated with losses of reactive forms of nitrogen (N) to the environment. Research has focused on losses to air and water due to the health, economic and environmental impacts of reactive N. Di-nitrogen (N2) emissions are still poorly characterized, both in terms of the processes involved and their magnitude, due to financial and methodological constraints. Relatively few studies have focused on quantifying N2 losses in vivo and fewer still have examined the relative contribution of the different N2 emission processes, particularly in grazed pastures. We used a combination of a high (15)N isotopic enrichment of applied N with a high precision of determination of (15)N isotopic enrichment by isotope-ratio mass spectrometry to measure N2 emissions in the field. We report that 55.8 g N m(-2) (95%, CI 38 to 77 g m(-2)) was emitted as N2 by the process of co-denitrification in pastoral soils over 123 days following urine deposition (100 g N m(-2)), compared to only 1.1 g N m(-2) (0.4 to 2.8 g m(-2)) from denitrification. This study provides strong evidence for co-denitrification as a major N2 production pathway, which has significant implications for understanding the N budgets of pastoral ecosystems.

No MeSH data available.


Related in: MedlinePlus